My daughter has a 1969 Beetle which is an Autostick. Long story short, I had to replace the head studs a while ago and since the motor has been back together I can never get it to run right.

What happens is I get it running, and it idles beautiful, but I let it warm up and then I try and adjust the carb and what happens is that the engine ends up hesitating and back fires when I try to rev it. Then I find that cylinders 1&2 aren't firing, so I replace the plugs and at first it's all good again, but then we go around again and cylinders 1&2 stop again.

I know it's not the distributor, because when I take the leads off the plugs while the engine is running, I get a nice powerful shock.

Any ideas? Tomorrow I'm planning on pulling the inlet manifold off and replacing the gaskets in case it's letting air in, but I'm not sure if it's the issue. I didn't have any brake cleaner so I turned the garden hose on and wet everything that could be letting air in, but the engine kept on idling; maybe by that time cylinders 1&2 had already stopped firing.

Any tips will be very much appreciated. This issue has been going on for over 12 months, but due to illness I have never been able to stick at it long enough to solve the issue, and in the meantime my beautiful daughter doesn't get to drive her first car

First: Use an unlit propane torch for vacuum leaks, you absolutely don't want to use brake cleaner, esp in a confined space, it can kill you after it burns in the combustion chambers, forms very toxic gasses. Temporarily set the mixture a touch lean for best results with the propane, if its too rich adding more fuel won't change RPM.

Are the plugs oiling? Could be lined up ring gaps, it happens, I have seen it happen at 50K miles, although usually just one hole. The rings tend to rotate a bit in use. A compression test usually shows a ~dead hole.

I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

A compression test is definitely in order. Pulled head studs are frequently encountered on the `68/`69 H5 cases (and their B5 brethren) due to the inferior alloy used in those. Did you get the heads flycut-to-clean to reestablish a good sealing surface between them and the cylinders? Were any spacers used under the cylinders or between them and the heads?
I'm suspecting low compression on the RH side is the root problem. If it's less than ~105 problems like you describe are commonplace. Make sure the valve lash isn't too tight. Do you recall what seals were used under the rocker stands? Should have been the thin O-rings, NOT the "wedding-band" ones - only some earlier heads have room for those, on `69 heads they would squish out leaving the rockers "rubber-mounted" which will cause lash to change dramatically with temperature...at least until they fall off completely.

I recently installed a CB distributor on my car so I have a spare 009 distributor that I know works. I installed that today and it immediately fired up! I didn't keep it running for a long time, but I did go for a spin around the block and it ran as good as I expected with the timing set by ear. Tomorrow I plan on installing the old vacuum distributor that was on the car before I installed the electronic dizzy which evidently is not too reliable. It's annoying though considering that the electric dizzy has only been on the car for a couple hours, if that.

I had a Pertronix conversion to my 009 distributor and I thought it died so I replaced it with another unit then sent it back to them. This was many, many years ago but I now don't think it was the Pertronix unit but something else but, like anything else, the conversions are certainly quite capable of taking a dump on you especially if something else goes wrong.

For an Auto Stick, the stock distributor is the best option. They have both centrifugal & vacuum advance mechanisms and are curved to complement the torque converter's stall speed.
If it's a 4-speed vacuum-only dizzy, IMO you may as well leave the 009 in there.

In nearly every case, timing "by ear" will result in more advance than ideal...may seem to run just fine, but hard on the pistons & rings.

There're about a half-dozen singleport Auto Stick distributors with similar characteristics, any of which should be fine. The 10-digit Bosch number stamped into the housing provides positive identification, but with any of them you should be able to twist the rotor slightly in relation to the bottom end of the shaft and observe it snap back when released (the 4-speed models have a one-piece shaft). All of the SP Auto Stick dizzies are set to 0° static (or at idle with a strobe, with hose disconnected) and have 8-12° vacuum advance plus another 25-28° of centrifugal which isn't all in until nearly 4000 RPM.

I've spent pretty much 3 whole days on the beast and I think I might have solved the problem.

First thing I did was pulled all the intake stuff. I made my own paper gaskets using the proper stuff and sanded the bases of the manifolds on a glass window. I did the same to what the carb bolts into and it was far from flat. Being steel, I had Buckley's of getting that flat, but I think I solved that part after having to use a spacer anyways due to the alternator and I used a couple gaskets and some of the orange gasket stuff, which I don't normally every use. I after carefully torquing up the carb I let it sit for 24 hours.

The next day I put another set of plugs in it and fired it up, and it ran! I took out for a drive and I found that out always hesitated when I accelerated from idle. I installed the distributor that I thought was faulty hoping with vacuum advance it might not bog down so much, but it still did. Playing around with the accelerator pump didn't help.

I then started playing with the carb because I felt as though it was fuel related. I noticed that while is was idling, more and more smoke came out of the exhaust. I pulled the idle jet and installed a leaner jet. Lol by this time the plugs had fouled so I swapped them out but it still hesitated to the point that it stalls. I then changed took a washer out from under the float and I changed the air correction jet. After all that, I go for another drive and 'i think' it ran sweet, because it didn't stall where it did every other time, but I almost ran out of petrol lol.

So anyways, today I went and took a drum to the petrol station and I'll put the 20 litres in the bug tomorrow morning and hopefully I have indeed fixed it. I'm convinced though that if the problem remains, it has to be the carb. It was a Chinese carb, but it's now a Frankenstein as it has many of the German parts inside it!

Time to check fuel pressure or go to a self limiting electric pump...
I've been running the same old carter clacker for 20 years, for the last ~10 or so its been a FI feed pump.

Wait---What color smoke?---black is excess fuel, white is oil.
Oil can foul plugs very quickly, some oils burn cleaner than others...
I remember one time awhile back (~35 years ago ) I was burning oil like crazy on a relatively new set of Cofap P&L, had to run Quaker State, it fouled the plugs in minutes with GTX...
The iron oil rings turned out to be totally bald in <10K miles, someone forgot a process step in Brazil I guess.

Oil has changed a lot in the last few years so don't use that as anything but an example of what can happen.

I, for one, regularly embrace our new robot overlords, as I am the guy fixing the robots...

I really think it's electrical. When I get some time I'll swap over the coil, and I'll run the bare minimum wires to the coil so I bypass the ignition switch, and disconnect the power to the Autostick solenoid and tacho, and see how I go.